Field of the Invention
The present invention relates to an imaging apparatus, an imaging system, and a method for driving the imaging apparatus.
Description of the Related Art
An imaging apparatus is known which has a plurality of pixels containing a plurality of photoelectric conversion units arranged under the same microlens, and outputs a signal based on one photoelectric conversion unit and a signal based on another photoelectric conversion unit. This imaging apparatus uses signals of at least two photoelectric conversion units provided under the same microlens, measures a phase difference, detects a focus. Furthermore, the imaging apparatus adds up the signals of the above described two photoelectric conversion units, and thereby obtains an imaging signal. For instance, Japanese Patent Application Laid-Open No. 2013-090160 discloses a technology of adding and reading out signals per pixel unit and solely reading out a signal from each photoelectric conversion unit, in an imaging element in which each pixel has a plurality of photoelectric conversion units and which reads out signals sent from the respective pixels.
However, in Japanese Patent Application Laid-Open No. 2013-090160, a study has not sufficiently been conducted for increasing the speed of reading out an added signal of signals based on the plurality of photoelectric conversion units, and reading out a signal for measuring a phase difference, which is sent from a part of the plurality of photoelectric conversion units.
The technology that will be described below relates to an imaging apparatus, an imaging system and a method for driving the imaging apparatus, which can increase the speed of an operation.